1. Field of the Invention
This invention relates to a nicked cutting tool, more particularly to a cutting tool suitable for cutting and machining fiber-reinforced composite materials.
2. Prior Art
Fiber-reinforced composite materials using fibers such as aramid fiber and carbon fiber have been widely used. The fiber-reinforced composite materials are formed by coating the surface of base metal such as steel materials with these fibers to unify them, and because of their superior mechanical and physical properties, they are used very often particularly in the aircraft industries and space industries.
When cutting and machining such fiber-reinforced composite materials by cutting tools such as twist drills, reamers, end mills, and milling cutters, special cutting performances different from those required in cutting normal metallic materials are demanded.
For example, 1. fibers should be cut so as not to form naps, separations, burrs or the like; 2. since the thermal conductivity of the fiber is low, the heat generated by cutting should be efficiently transmitted to the cutting tool to be released; 3. cutting should be performed at low temperature so as not to melt the fiber due to the temperature rise of the workpiece; and others.
Cutting tools capable of machining efficiently by providing nicks on the twisted cutting edge so as to discharge the chips smoothly when cutting have been well known, but in many of the existing cutting tools, nicks formed on lands were orthogonal to the longitudinal axis of the tool. There are some tools in which nicks were inclined to the longitudinal axis of the tool, but anyway, in the existing cutting tools, all the nicks installed on lands were in an identical direction. Because it was designed so that the above actions and effects could be brought about during the rotation in a specific direction because the rotating direction of the cutting tool is determined in one.